| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [is] impossible to be [adj] | 23 |
|
| 2 | is impossible [prep] be [adj] | 19 |
|
| 3 | [is] impossible [prep] be sure | 7 |
|
| 4 | [is] impossible [prep] be certain | 7 |
|
